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authorTejun Heo <tj@kernel.org>2016-03-08 11:51:26 -0500
committerTejun Heo <tj@kernel.org>2016-03-08 11:51:26 -0500
commitf6d635ad341d5cc0b9c7ab46adfbf3bf5886cee4 (patch)
tree0dc1bbf73f89b562748e1e2e57ca2262e9903b5e /include/linux/cgroup-defs.h
parente4857982f49d21c05a84351b56724bf353022355 (diff)
cgroup: implement cgroup_subsys->implicit_on_dfl
Some controllers, perf_event for now and possibly freezer in the future, don't really make sense to control explicitly through "cgroup.subtree_control". For example, the primary role of perf_event is identifying the cgroups of tasks; however, because the controller also keeps a small amount of state per cgroup, it can't be replaced with simple cgroup membership tests. This patch implements cgroup_subsys->implicit_on_dfl flag. When set, the controller is implicitly enabled on all cgroups on the v2 hierarchy so that utility type controllers such as perf_event can be enabled and function transparently. An implicit controller doesn't show up in "cgroup.controllers" or "cgroup.subtree_control", is exempt from no internal process rule and can be stolen from the default hierarchy even if there are non-root csses. v2: Reimplemented on top of the recent updates to css handling and subsystem rebinding. Rebinding implicit subsystems is now a simple matter of exempting it from the busy subsystem check. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/cgroup-defs.h')
-rw-r--r--include/linux/cgroup-defs.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 590291d56049..34b42f03fcd8 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -451,6 +451,19 @@ struct cgroup_subsys {
bool early_init:1;
/*
+ * If %true, the controller, on the default hierarchy, doesn't show
+ * up in "cgroup.controllers" or "cgroup.subtree_control", is
+ * implicitly enabled on all cgroups on the default hierarchy, and
+ * bypasses the "no internal process" constraint. This is for
+ * utility type controllers which is transparent to userland.
+ *
+ * An implicit controller can be stolen from the default hierarchy
+ * anytime and thus must be okay with offline csses from previous
+ * hierarchies coexisting with csses for the current one.
+ */
+ bool implicit_on_dfl:1;
+
+ /*
* If %false, this subsystem is properly hierarchical -
* configuration, resource accounting and restriction on a parent
* cgroup cover those of its children. If %true, hierarchy support